Commitments and Contingencies - Summary of Changes in Contingent Consideration Obligations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Business Acquisition, Contingent Consideration [Line Items]
Balance, End of Period	$ 107,342		$ 107,342
Level III [Member]
Business Acquisition, Contingent Consideration [Line Items]
Balance, Beginning of Period	131,231	5,900	142,219	5,900
Acquisition of Stone Tower		117,700		117,700
Payments	(20,377)		(44,796)
Change in fair value	(3,512)	(2,985)	9,919	(2,985)
Balance, End of Period	$ 107,342	$ 120,615	$ 107,342	$ 120,615